530 GASTROPODA. [0 pisthobrancfi ia. 



Fam. SCAPHANDRID.E, Fischer. 



Animal with a short cephalic shield, truncated posteriorly ; no 

 tentacles, the eyes deeply imbedded ; epipodial lobes well developed ; 

 3 calcareous stomachal plates, two broad and paired, one narrow and 

 single : they are not tuberculate. Eadula having the central tooth 

 small, with a very large lateral on each side of it, and either a few 

 smaller marginals or none. 



Shell spiral, external, the spire sunken or concealed. 



The form of the shell is so various that no useful diagnosis of the 

 family can be drawn from that organ. 



This family differs from TornatinidcB in the obsolescence of pos- 

 terior lobes on the head-shield, in the well-developed radula. and the 

 large lateral epipodial lobes. It differs from Bullidce in the highly 

 specialised form of the radula-teeth and their small number in a trans- 

 verse row. 



The animals are carnivorous. 



Genus 1. CYLICHNELLA, Gabb, 1873. 



Cyliclmdla, Gabb, Proc. Acad. Nat, Sci. for 1872 (1873), 273. Type : 

 Bulla bidentata, d'Orbigny. Bullinn, Risso, 1826 ; not of Ferussac, 

 1822. Cylindrella, Swaiiison, Mai., 1840 ; not of Pfeiffer, 1840. 

 Cylichna, Loven, 1846 ; not Cylichnus, Burmeister, 1844. Cryptaxis, 

 Jeffreys, 1883 ; not of Lowe, 1854, nor of Reuss, 1865. ? Mnestia, 

 H. and A. Adams, 1854. Built nella, Newton, 1891. Clistaxis, Coss- 

 mann, 1895. Cyclina, Gray, 1857 ; not of Deshayes, nor Cydinus, 

 Kirby, 1837. 



Animal with a long head-disc, truncated in front and behind. 

 Mouth armed with a pair of jaws composed of imbricating prickly 

 elements ; gizzard containing 3 equal oval calcareous plates. Radula 

 with the central tooth small, erect, with a bilobed serrate apex ; 

 laterals large, hooked, with a series of fine denticles near the edge ; 

 marginals small, simple, from 2 to 5 in number on each side. 



Shell rather small and subcylindrical. the spire sunken and um- 

 bilicate or closed and concealed by the calloused inner lip ; mode- 

 rately solid, smooth or with spiral strife ; aperture as long as the shell, 

 narrow above, somewhat dilated toward the base ; columella rather 

 thickened, simple or somewhat sinuous ; outer lip receding toward 

 the suture. 



Distribution. World-wide. 



Fossil in the Cretaceous and Tertiary. 



KEY TO SPECIES. 



A. Shell without spiral lines, inequidistant sharp axial striae. . . . striata. 



B. Shell with spiral sculpture. 



a. With dense microscopic undulating spiral lines . . . . pygmcea. 



aa. The tine close spiral lines almost ' effaced medially, wider 



spaced above . . . . . . . . . . Thetidis, 



